The mansion was built in 1789 as a summer home by William Lewis, one of the most accomplished and well-known lawyers of his generation.
Joseph Hemphill purchased Summerville in 1821 and during the next decade extensively altered the house. He added the two Greek Revival wings, painted the house a light pink and named it Strawberry Mansion.
In 1844, the mansion and grounds were purchased by George Crock and used as a dairy farm, until the city purchased it for Fairmount Park in 1867.
From 1867 until 1930, the Fairmount Park Commission leased the mansion for use as a restaurant. Then in 1930, the Fairmount Park Commission turned the building over to the Committee of 1926 of Pennsylvania, a group of civic-minded women. The ladies renovated the mansion and opened it to the public in March 1931. They continue to administer it for the Fairmount Park Commission as a showplace of Federal and Neo-Classical styles with a third floor of antique dolls and toys from 50 states.